Abstract-Millimeter-Wave and Terahertz-Wave Applications Enabled by Photonics

Nagatsuma, T. Hisatake, S. ; Fujita, M. ; Pham, H.H.N. ; Tsuruda, K. ; Kuwano, S. ; Terada, J.
Graduate School of Engineering Science, Osaka University, Toyonaka, Japan 
http://ieeexplore.ieee.org/xpl/abstractAuthors.jsp?reload=true&arnumber=7350105

This paper describes continuous millimeter-wave and terahertz (THz)-wave applications, where telecom-based photonics technologies are efficiently employed to enhance their performance. First, 300-GHz-band wireless communications are described toward real-time error-free transmissions at 50 Gbit/s and beyond. Next, a novel approach to increase a phase measurement sensitivity in THz frequency-domain spectroscopy systems is explained, and a similar technique is successfully applied to the visualization of electric-field radiation and propagation. Finally, as a futuristic study, the manipulation of THz waves with a concept of photonic crystals and its possible applications to platforms in THz integrated systems are presented.

Abstract-Terahertz balanced self-heterodyne spectrometer with SNR-limited phase-measurement sensitivity.

Hisatake S, Koda Y, Nakamura R, Hamada N, Nagatsuma T.

http://www.ncbi.nlm.nih.gov/pubmed/26480182


Photonics-based frequency-domain terahertz (THz) wave measurement systems have received significant attention in both scientific and industrial fields due to their high-frequency resolution. Highly sensitive phase-measurement systems have been desired in the chemical, material, and biomedical sciences to facilitate microanalysis of materials. Here, we demonstrate a balanced self-heterodyne technique that, for the first time, simultaneously offers wide frequency tunability of more than 2.5 THz and high phase sensitivity, which is limited only by the signal-to-noise ratio (SNR) of the amplitude measurement. Using free-running lasers for THz wave generation and detection, the experimentally achieved minimum detectable optical path length change was 400±50 nm at 2 THz for a SNR of 37.7 ± 0.7 dB, even though the theoretically expected SNR-limited value was 310 ± 20 nm. The phase measurement sensitivity of our system is almost one order of magnitude better than that of the conventional systems in which limitations arise from phase instabilities in the optical components and/or laser linewidth.